Heat treatment rack



April 14, 1959 F. w. GARNER 2,882,032

' HEAT TREATMENT RACK Filed Jan. 13, 1955 IN V EN TOR.

W FRED w. GARNEIR 2 Agem nitedStates P t 01c HEAT TREATMENT RACK Fred W.Garner, .Los Angeles, Calif., assignor to Lockheed Aircraft Corporation,Burbank, Calif. Application January 13, 1955, Serial No. 481,588

2 Claims. (Cl. 263-47) This invention relates to an improved heattreatment rack to support articles being heated and then quenched todevelop their full strength after forming to shape.

Heretofore, such heat treatment racks have been built up as stiff weldedstructures which are rigid and inflexible and therefore soon warp andsag out of shape due to the repeated heating and quenching thereof innormal use. Such racks are used to carry parts through sequentialheating and quenching cycles by pushing the racks onto an elevator to belifted into a heating oven, and after the heating cycle, lowereddirectly into a quenching tank. It is therefor an object of thisinvention to provide a heat treatment rack that will survive repeatedexpansion and contraction due to the heating and quenching cycleswithout warping, and to that end I provide bolted braces and slip jointsfor pliability in a vertical plane while maintaining rigidity in planform by the use of cross-bracing.

It is a further object of this invention to provide a multiple wheeledheat treatment rack of the type described wherein the rack isalternately braced to stand upright and straight in line with boltedslip joints for vertical pliability, whereby each of the wheels carrytheir share of the load on an uneven floor. The vertical pliability ofthe rack allows the wheels to set solidly on the ground or the ovenhoist with the Weight distributed over the multiple wheels thuseliminating any tendency of the rack to warp or sag into contact withthe oven walls during the heating cycle.

It is another object of this invention to provide a light weight, easilyhandled rack of the type described to facilitate loading and unloadingand reduce the heating and quenching times of the heat treatment cycle.

Other objects and advantages of my invention will appear from thefollowing description taken in connection with the accompanyingdrawings, wherein:

Figure 1 is a perspective view of a heat treatment rack embodying thenovel features of my invention;

Figure 2 is an enlarged detail section of one of the wheel mounts, takenon the line 22 of Figure 1;

Figure 3 is an enlarged detail section at right angles to the showing ofFigure 2, taken on the line 33 of Figure 1.

As shown on the drawings:

The heat treatment rack of this invention comprises a loosely jointedrectangular framework connecting a series of axles each carrying twowheels 11. The framework comprises spacer tubes 12 between the ends ofeach axle, which tubes have loose or free telescopic connections withtubes 13. In the drawings I have shown the end parts of the tubes 13engaged or telescoped in the end portions of the spacer tubes 12 withclearance, that is the inside diameters of the tubes 12 are greater thanthe outside diameters of their related tubes 13. The ends of the spacertubes 12 are retained in the tubes 13 for limited axial and universalmovement by bolts 27 loosely fitting their respective openings. Whilethese loose joints perrnit relative movement between the tubes 12 and 132,882,032 Patented Apr. 14,

the tubes are positively connected against separation and relativemotions of the related tubes are limited, flattened ends 14 boltedtogether at 15 and to slip tubes- 16 protruding from the ends of the.axles, as best shown in Figures 2 and .3. These connections, 15comprise bolts 17 freely passing through oversize vertical openings inthe superimposed flattened ends 14,.and tubes .=l6 and; the

tubes 16 have play or loose engagement in their respective axles 10, allas shown in Figures 2 and 3. These arrangements provide slack or give atthe bolted connections, and the rectangular frame so formed is laterallyor transversely stilf but vertically pliant to allow any wheel or axleto rise or fall to conform to an uneven ground. The rectangularity ofthe frame is further maintained by crossbracing 30 and a stiif wirescreen 18 laid over the axles and fastened to the side tubes to assistin resisting lateral distortion of the rack 12. The screen 18 alsoserves to prevent articles being treated from dropping through theframework to the ground. u

An upper framework is formed similar to that just described with crossmembers 19 and longitudinal spacers 20 having slip tubes 21 bolted inthe ends thereof. These frame members are loosely connected in the samemanner as the tubes 12, 13 and 16 of the lower framework. Uprights 22 ateach wheel location similarly have slip tubes 23 at each end, the upperand lower frameworks being tied thereto by clips 24 engaged under thehead of the bolts 17 with their other ends bolted to the slip tubes 23.In alternate panels diagonal braces 25 engage between bolts 26 throughthe uprights 22 and the slip tubes 23 and the spacer tube 12 connectingbolt 27 to its slip tubes 13.

The upper framework is provided with cross-bracing 30 and screenstiffening 28 similar to the screen 18, which screen serves as a supportfor hooks (not shown) used to suspend the articles to be heat treated.By so suspending the articles, warpage thereof is greatly reduced duringprocessing and the articles are uniformly heated and quenched during theoperation. The uprights 22 carry spacers 29 with books to support anintermediate shelf if desired.

The heat treatment rack above described provides a verticallyarticulated multiple wheel rack wherein individual wheels may settle orbe lifted by ground irregularities while carrying their share of theload. This articulation is limited to up and down movement of the wheelsby the cross-bracing and screens stiffening both the upper and lowerframeworks against lateral deflections. While the relative movement atany one metal to metal joint is small it is yet enough to prevent thetransmission of expansion and compression strains through the joints andthus prevents warping or sagging of the rack under load and thermalstresses during the repeated heat treating cycles of heating and rapidquenching.

Having thus described my invention and the present preferred embodimentsthereof, I desire to emphasize the fact that many modifications may beresorted to in manner limited only by a just interpretation of thefollowing claims.

I claim as my invention:

1. A heat treatment rack for carrying articles to be heated and quenchedcomprising a plurality of axles carrying wheels for supporting the rack,each axle comprising a wheel spacing tube and a slip tube bolted to thespacer tube, top and bottom frameworks comprising spacer tubes betweenthe axles, slip tubes loosely telescopically engaged with the ends ofthe spacer tubes for limited relative movement, loose-bolt connectionsconnecting the axle slip tubes to the adjacent slip tubes of theframework spacer tubes for limited relative move- 'ment, vertical spacertubes having slip tubes tied to the ,loose-bolt connections connectingthe axle and framework slip tubes, and diagonal braces connecting theframework spacer tubes and vertical spacer tubes in alternatepmels,whereby to form a laterally stiff but vertically flexiblerackincapable'of developing thermal stresses at t the joints.

References Cited in the file of this patent UNITED STATES PATENTS Meyerf July 21, Smith Feb. 8, Jarvis et al Nov. 15, Longfellow Sept. 17,Jackson Nov. 16, Menough July 1, Clark Mar. 20,

FOREIGN PATENTS Great Britain Apr. 26,

